1. Field of the Invention
The invention relates to a flat commutator and to a method for the production of a flat commutator. More particularly, the present invention utilizes conductive carbon elements and is especially useful in environments which are corrosive to copper.
2. Description of the Prior Art
It is already known to construct brush contact surfaces of commutators of carbon segments when said switches operate in an environment corrosive to copper, such as, a fuel which includes methanol.
German Utility Patent 89 07 045 discloses a flat commutator of the aforementioned type wherein the carbon segments have journals on their bottoms which penetrate through openings in the segment-supporting parts which are of copper and which support them and engage in the hub body which supports the segment-supporting parts anchored in said body, which are separated from one another by separation gaps.
In another known flat commutator intended for operation in an environment reacting with copper (German Utility Patent 89 08 077.7), the segments forming the brush contact surfaces are of a composite material; carbon on the side forming the contact surface; and, metal and plastic on the side turned toward the carbon segment-supporting part which is soldered thereto. The carbon segment-supporting part, is in turn connected securely with a hub consisting of a molded plastic material.
There is no need for concern about extensive wear or abrasion occurring in the area of the brush contact surfaces of these types of switches. Despite the presence of the carbon segments, however, large areas of the segment-supporting parts are exposed to the influence of the aggressive environment. Therefore, until this invention this has been taken into consideration at some cost, since it is not possible to provide all of these areas with protective covering following completion of the manufacture of the commutator. This is especially true for the side surfaces of directly adjacent carbon segment-supporting parts which are turned toward one another. In known commutators the side surfaces of the carbon segments define air gaps on account of the separating of the parts. Another drawback of prior art devices is that because of the journals on the carbon segments, which necessitate undertaking the pressing of the carbon segments on the segment-supporting parts, the manufacturing process is completed only with great difficulty and the formation of a good contact between the carbon segments and the segment-supporting parts supporting them is not permanently guaranteed.